The Centers for Disease Control and Prevention says that within the last four months there have been more than 140 outbreaks in the US that have been caused by the new Sydney strain of Norovirus.
The contagious bug causes bouts of diarrhea and vomiting.
Health officials say the new strain isn't unusually dangerous, but many people may struggle not be able to fight off its gut-wrenching effects.
Norovirus often spreads in places like schools, cruise ships and nursing homes.
